Motor fuel product



V Patented Aug. 14,

UNITED STATES 1,910,339 4 MOTOR FUEL rrtonuc'r,

Thomas H. Rogers and Vandcrveer Voorhees. Hammond, Ind., assignors toStandard Oil- Company, Indiana Whiting, Ind., a corporation of NoDrawing. Application sum 20,1930,

Serial No. 416,110 r '1 Claims. (01. 4 -9) The present invention relatesto improvements in hydrocarbon motor fuel products of the character ofgasoline, and has to domore particularly with motor fuel productsderived by the cracking ofhigher boiling hydrocarbon oils of such" typesas display a tendency to form gum or resinification products on storage,even after refining treatment with a dilute sulfuric acid such as sul-.

2o cracked gasoline, having an anti-knock valuesomewhat greater but notsubstantially greater than straight-run gasoline; a somewhat lower Baumgravity than straight-run gasoline; containing a moderate proportion ofunsaturated compounds as determined by combined absorption andpolymerization by sulfuric acid in accordance with the method ofdetermination hereafter set forth; and being in general of such acharacter that the constituents thereof which tend to form gum onstorage and handling are readily removed by treatment with sulfuric acidto produce a product comparable in that respect to straight-rungasoline. Motor fuel products of the second general class, hithertoderived principally from vapor phase processes or very high temperaturepressure cracking processes, have anti-knock values substantially higherthan straight-run gasoline; have a much lower A. P. I. gravity; containlarge amounts of unsaturateds as determined by sulfuric acid absorptionand polymerization; and require excessive treatment with sulfuric acid,with very substantial losses, to remove potential gum-formingconstituents.

Although it cannot be said that there is ahard and fast line between thetwo typesof products, the former type of product, with 425 F. end point,will in general have an anti-knock value not exceeding an equivalent of1.2 cubic centimeters of tetra-ethyl lead per gallon of straight-runMid- Continent gasoline; an olefin content as determined by suliuricacid absorption and polymerization of not over 40%; an A. P.-I. gravityof 56 to 59; and an oxygen absorption induction period greater than 125minutes, as determined by,

56 the test hereinafter set forth.- The second type of product, whichmay be designated as the vapor phase type, will in general have ananti-knock I value equivalent to at least 1.2 cc. tetra-ethyl lead pergallon straight-run Mid-Continent gasoline,

an A. P. I. gravity of about 49 to an unsat- 60 urated content asdetermined by sulfuric acid absorption and polymerization exceeding 40%,and usually above 45%; and an oxy en absorption induction period of lessthan 125 minutes.

The latter type of product in general tends to form gum, even on storagein the dark, and under like conditions, tends to lose its anti-knockprop: erties. 'lhe same tendencies may exist, to a greater or lessextent, in products of thefirst mentioned type and, thepresent/invention may be employed in connection therewith, althoughparticularly intended for use in connection with products of theso-called vapor-phase cracked type.

Thu products of certain processes commonly designated as liquid phase orliquid-vapor phase cracked products, although having a lower unsaturatedcontent than vapor phase cracked products, as-shown by combinedabsorption and polymerization by sulfuric acid, have gum-formingproperties similar to those of vapor phase cracked products. The presentinvention may be applied. in connection with such products, as well aswith such highly cracked products as are derived by drastic or hightemperature cracking or destructive distillation of bituminousmaterials, such as coal, peat, lignite, and the like.

In determining the oxygen absorption induction period, by which anindication of the potential gum-forming properties of the gasoline onstorage and handling may be secured, the following procedure may beemployed; 100 cubic centimeters of the motor fuel or'gasoline to betested are placed in a one liter flask, the total volumetric capacity ofwhich is 1150 to 1200 cubic. centimeters. The gasoline is maintained atabout 212 F. by heating in a steam bath while an oxygen atmosphere ismaintained in the flask under a substantially constant pressure ofvabout 2% atmospheres. The flask is vigorously agitated and the volume ofoxygen absorbed is measured at frequent intervals. The oxygen absorptionis characterized by an initial period in which relatively small amountsare absorbed and subsequent to this period there is a rapid increase inthe rate of absorption. This initial period of slow absorption isdesignated the induction period, and its end is regarded as the point atwhich oxygen absorption under the conditions stated reaches a rate of 1cubic centimeter per minute. If the oxygen absorption is plotted againstthe time in minutes with equal distances on the coordinates for time inminutes and absorption in cubic centimeters, it will be evident that theend of the induction period will be indicated upon the curve by thepoint where the tangent to the curve has a slope of 45. The length ofthe induction period, as determined by this test, provides a fairlyaccurate indication of the potential gum-forming behavior of the motorfuel product on storage and handling.

The motor fuel products with which the present invention is primarilyconcerned, are produced from cracked distillate products of thevapor-phase cracked type which, after treatment with dilute sulfuricacidof 50 to 70% strength, have an oxygen absorption induction period ofless than 125 minutes. The following procedure has been employed inproducing such a product.

A hydrocarbon oil, preferably a distillate product heavier thangasoline, is forced through a continuous coil in a heating zone andbrought therein to an outlet temperature of 825 to 975 F. whilemaintaining thereupon a pressure exceeding 200 lbs. under conditions toproduce from 15 to 35% of hydrocarbons in the gasoline boiling pointrange in the products leaving the coil. The material leaving the coil ispreferably reduced in pressure and fractionally condensed to separatethe hydrocarbons in the gasoline range of boiling points as adistillate. The vaporization is controlled, or the distillate productmay be rerun, to produce a material conforming to the desiredspecifications, for example, to 425 F. end point. Such,a material has agravity of 48 to 56 Baum as compared with 58 to 60 Baum for astraight-run gasoline of similar boiling range from Mid-Continent crude.The product, without treating, is found to have an oxygen absorptioninduction period of about 35 to '10 minutes. It is suitably treated withdilute sulfuric acid, say 60% acid, to the extent of 6 lbs. of such acidper barrel of distillate. The loss on treating is about /2%, the colorof the product is not substantially altered, but is substantiallystabilized and the oxygen absorption induction period is increased to tominutes. In determining the unsaturateds in such a product it shows acombined absorption and polymerization loss of 50% to 70% when the testis made with 90% sulfuric acid. This loss is determined by subjecting agiven volume of the material to treatment at room temperature with twovolumes of 90% sulfuric acid, separating the remaining oil from the acidlayer and redistilling the unabsorbed oil to produce a distillate havingthe same end point as the original material treated. The loss in volumerelative to the original material is that which is designated as thecombined absorption and polymerization loss.

A treated distillate product produced as hereinbefore described, orother cracked products having a. tendency to form gum or resinificationproducts on storage, is treated by adding thereto a small proportion ofan organic inhibiting agent or anti-oxidant having reducing propertiesand contaning a polyhydroxy aromatic radical. Such substances areemployed in proportions of, in general, less than 0.1% and preferablyless than 0.05%, and substantially stabilize the product against gumformation and resinification, and also against loss in antiknock. Thisstabilization is indicated by an increase in the .omgen absorptioninduction period of the products to which they are added. As examples ofsuch materials, we may employ hydroquinone, pyrogallol,nicotine-pyrogallate, amylgallate, resorcinol, cate chol, and the like.The alkyl esters of gallic acid employed in our invention have thefollowing general chemical formula COPR HO OH wherein R represents analkyl radical.

The specific activity of these materials varies to a considerableextent, all of them, however, being effective in inhibiting thegum-forming properties of the motor fuel product and preventing itsdeterioration, for example, by decrease of its anti-knock value, andthese properties are indicated by an increase in the induction period ofthe product. It is preferred to employ those which, when added to avapor phase type of product as hereinbefore set forth in proportions of0.05% or less, will increase the induction period to above 125 minutesand preferably to 300 minutes or more. Thus with the product prepared asabove described, and which after dilute acid, treatment, has aninduction period of 47.5 minutes and the lead eqiih alent of 1.7 cubiccentimeters tetra-ethyl lead per gallon of straight-run Mid-Continentgasoline, the addition of 0.01% of pyrogallol. increased the inductionperiod to above 650 minutes. The addition of 0.01% ofnicotinepyrogallate to the same material increased the induction periodto 565 minutes. With another, similarly prepared product, which. afterdilute acid treatment, had an induction period of about 90 minutes, theaddition of 0.0074% amylgallate increased the induction period to about195 minutes; The addition of hydroquinone in proportions of 0.005 to0.05% likewise causes a substantial increase in the induction period ofthe fuel product. I

The results secured by the application of the oxygen absorptioninduction test, as hereinbefore described, have been found by repeatedexperiment to definitely indicate the behayiorof the motor fuel product,both in its tendency to form gum and lose in anti-knock value. Onstorage of the gasoline for considerable periods, say six to eightmonths, such as are customary in commercial practice, such motor fuelswithout added constituents are found to increase substantially in theirgum test and to fall off almost completely in anti-knock value. Theaddition of the compound containing a polyhydroxy aromatic-radical, suchas those hereinbefore referred to, very substantially or completelychecks the rise in gum test andcdecreases the loss in anti-knock. Ingeneral, the extent towhich the increase to gum test and decrease inanti-knock is effected may be correlated with the increase in theyoxygen absorption induction period; the greater the once-- tiveness ofthe particular compound added in increasing the. oxygen absorptioninduction period, the greater in general is its effectiveness inpreventing guni formation and loss in anti-knock on storage. Theseimprovements in the proper- Motor fuels produced in with the presentinvention may be recognized by the fact that their oxygen absorptioninduction period is decreased by successive treatments with dilute acidand dilute alkali, for example, by successive washing of the fuel with50% sulfuric acid and 10% alcoholic caustic soda solution.

If desired, the anti-knock value of the motor fuel described herein maybe increased by the addition in small amounts of tetra-ethyl lead orother suitable material, and it is contended that the accompanyingclaims shall include the products of the type herein set forthregardless'of the addition thereto of tetra-ethyl lead or othermaterials modifying their fuel characteristics.

This application is in part a continuation of our prior applicationSerial No. 211,554, filed August 8, 1927.

We claim:

1. A motor fuel product comprising cracked hydrocarbon distillates whichnormally tend to deteriorate and develop gums, said product containing asmall proportion of a gum formation inhibiting agent selected from theclass consisting of nicotinepyrogallate and amylgallate.

wherein R. represents an 01!?! noon.

3. The method of p cracked hydrocarbon distiilates which deteriorate anddevelop gums on storage, by incorporating therein a small proportion ofa gum formation inhibiting agent selected from the class consisting ofnicotinecracked hydrocarbon fuel product having an anti-knock valueequivalent to upwards of 1.3 cubic centimeters tetra-ethyl lead pergallon of straight-run Mid-Continent gasoline and showing a loss ofupward of 40% by absorption and polymerization by sulfuric acid, byincorporating therein a minute proportion of, amylgallate.

6. A motor fuel product consisting substantially entirely of crackedhydrocarbon distillates which tend to deteriorate and develop gums,saidproduct containing a small proportion of amylgallate, whereby itstendencies to deteriorate and develop gums are inhibited.

'l. A motor fuel product consisting substan-. tially entirely of vaporphase cracked hydrocarbon distillates and being of a character showing aloss of upward of 40% by absorption and polymerization by 90% sulfuricacid, said product containing a small proportion of amylgallate.

